CompactRIO with two 9239

[cengiz]

Is it possible to record 8 channel data at 50kS/s/ch with 9012 Real-Time PowerPC Controller and two 9239 analog input modules, and send this data to a PC through the ethernet port. This sytem should be real-time or near to real-time. Thank you  in advance.

[Brian_K.]

Hi cengiz,

The short answer is yes.  The 9239 collects at 50 kS/s/ch, which means with 4 channels you collect each channel at 50/4 or 12.5 kHz.  With 2x9239 that is 8 channels going at 12.5 kHz.  How long that data takes to get back to your host PC is entirely system specific.  How long packets of data take to get across the network is difficult to determine, and is definitly not real-time deterministic.

The data will be deterministic, the communication will not.

[cengiz]

Hi Brian,

Thank you very much for your reply. I understand from your reply that  9012 Real-Time PowerPc is capable of doing such tasks.

But I think there is a little problem with 12.5Khz samling rate for each channel. 9239 module have 50 kS/s/ch simultaneous inputs.
So sampling rate should be 50kS/s simultaneous for each channel. In this case, total data to handle for the embedded processor and ethernet controller in the 9012 module is approximately 50*8*24 kbit/s = 9600 kbit/s (approximately;  without headers,etc). 100Mbit/s ethernet protocol is highly enough for such data to handle. But I had doubts about the Real-Time module and FPGA arrays of the chassis.  

9012 Real-Time PowerPC with two 9239 modules will be connected to a PC directly with an ethetnet cable. It won't be in a network formed with other devices. And PC is a brand new one (dual processors, 1GB RAM, Serial ATA, 7200 RPM 320 GB HDD, etc).

We also want to connect a usb hdd to the 9012 Real-Time module and use this disk for backup. Firstly, data collected from 8 channel will be written to the usb disk and then sent to the PC through the ethernet port. Do(es) you/anyone think CompactRIO can do this?

Best Regards

cengiz gezer

[JMota]

Cengiz,

---

@cengiz wrote:
Hi Brian,

But I think there is a little problem with 12.5Khz samling rate for each channel. 9239 module have 50 kS/s/ch simultaneous inputs.
So sampling rate should be 50kS/s simultaneous for each channel. In this case, total data to handle for the embedded processor and ethernet controller in the 9012 module is approximately 50*8*24 kbit/s = 9600 kbit/s (approximately;  without headers,etc).

---

You are correct with respect to the 50kS/s/ch. The module acquires simultaneously data from all channels at whatever rate you configure it to run, so you can do 50kS/s on each of the 8 channels at the same time.

Regarding the throughput question, I do not know the answer, but I suggest you look to these other discussions (until somebody can shed some light to the ethernet and USB throughputs):

http://forums.ni.com/ni/board/message?board.id=280&message.id=1458
" on my preliminary tests I was able to run 8 channels of DSA (2x cRIO 9233) with sustained 50kS/s (each channel contains 32bit data) and it looked to me that this is not by far the end."

http://forums.ni.com/ni/board/message?board.id=280&message.id=1696

Hope this helps.

JMota

[cengiz]

Thank you JMota,
The links you have given is exactly fitted to my problem.

It is suprised me that the throughput of CompactRIO has been a mystery since 2005. 
I agree that it is configuration and software dependent. But it should have a maximum limit.
I will look forward the replies.

Best Regards
cengiz gezer